Honestly, I would schedule yourself a day and fix your file structure. Having a clean structure will probably solve a lot of your problems off the bat, especially if you do the same things over and over. If your structure is
Hired Jobs > Job Name > jobname_estimate.doc
then the only thing your brain has to recall is that Job Name Q was the one with the estimate that went wonky/ was great and you'd like to copy/ is the one you need to refer to, and it will be simple to get to the necessary file.
It sounds like you have a lot of project support material, and that kind of stuff is usually best organized by project. Then, as others have said, if you'd like, you can keep an Active Project and a Done Project folder, but when all your stuff is organized by project all you have to do is move the whole "Job Name" folder into "Done."